The present invention is directed to electrode shorting, particularly to limiting and ameliorating electrode shorting in systems such as capacitive deionization water purification systems, which utilize a stack of electrode pairs, and more particularly to electrically protect an entire system from shutting down if a single pair of electrodes is shorted and to mechanically prevent a conducting particle from shorting a series of electrode pairs.
Various capacitive systems utilize a plurality or stack of electrode pairs. For example, one such system which utilizes stacks of electrode pairs is a capacitive deionization water purification system. An example of such a water purification system involving capacitive deionization utilizing carbon aerogel electrodes is described and claimed in U.S. Pat. No. 5,425,858 issued Jun. 20, 1995, to J. C. Farmer and is directed to a method for removing ionic solutes from water. The patented method makes use of pairs of carbon aerogel electrodes arranged with interelectrode gaps of small size (about 0.5 mm), through which the water is made to flow. Large stacks containing many electrode pairs are powered by a common power supply and are wired in parallel. Water flow passes through the gaps between the electrode pairs in series. In such a configuration of electrode pairs, if a single electrode pair becomes electrically shorted, such as by a conducting particle that spans the interelectrode gap, the entire stack could be shut down and considerable energy could be released. In addition, it would be possible for a single conducting particle to move through the stack, shorting a series of electrode pairs in sequence. One possible source of such conducting particles, and thus shorting of electrode pairs, would be due to debonding or fragmentation of the carbon aerogel electrodes. Thus there has been a need for means to prevent electrode pair shorting and to prevent migration of particles through the electrode pairs.
The present invention addresses both the shorting of a single electrode pair and the sequential shorting of a series of electrode pairs, either by carbon aerogel fragments or by any other particles or conducting solid materials.